Method for monitoring and controlling force applied on workpiece surface during electrochemical mechanical processing

Abstract

In one aspect, the present invention monitors a signal corresponding to a torque value of a motor that is used to maintain relative motion between a conductive top surface of a workpiece and a workpiece surface influencing device in the presence of physical contact between the conductive top surface of the workpiece and the workpiece surface influencing device. In another aspect, the present invention uses the signal to control a force applied to a top conductive surface of a workpiece during electrotreatment.

1. A method of monitoring force applied to a top conductive surface of a workpiece during an electrotreatment process that operates upon the conductive surface using an electro treatment solution, the method comprising the steps of:
 performing an electrotreatment process on the conductive surface using a potential difference created between the conductive surface and an electrode during at least a portion of the electrotreatment process and the electro treatment solution disposed between a workpiece surface influencing device and the conductive surface of the workpiece, the electrotreatment process including maintaining relative motion between the workpiece surface influencing device and the conductive surface of the workpiece in the presence of physical contact between the workpiece surface influencing device and the conductive surface of the workpiece, whereby the relative motion in the presence of the physical contact cause the force between the workpiece surface influencing device and the conductive surface of the workpiece; and 
 monitoring a signal obtained that corresponds to a torque value of a motor that is used to maintain the relative motion in the presence of the physical contact during the electro treatment process. 
 
   
   
     2. The method according to  claim 1  further including the step of:
 using the monitored signal that corresponds to the torque value to control the force during a subsequent portion of the electro treatment process. 
 
   
   
     3. The method of  claim 2  wherein during the step of electrotreating there is included another portion of the electrotreatment process wherein there is not any physical contact between the workpiece surface influencing device and the conductive surface of the workpiece. 
   
   
     4. The method of  claim 2  wherein during the step of electrotreating the force remains within a predetermined range. 
   
   
     5. The method of  claim 2  wherein, during the step of using, a change in the monitored signal corresponding to the torque value that exceeds a determined threshold will cause the controlling of the force during the subsequent portion of the electrotreatment process by changing a displacement between the conductive surface and the workpiece surface influencing device. 
   
   
     6. The method of  claim 5  wherein the displacement between the conductive surface and the workpiece surface influencing device is changed by altering a vertical position of a workpiece carrier to which the workpiece is attached. 
   
   
     7. The method of  claim 6  wherein a full face of the conductive surface of the workpiece physically contacts the workpiece surface influencing device during a period of time with the relative motion. 
   
   
     8. The method of  claim 5  wherein the displacement between the conductive surface and the workpiece surface influencing device is changed by altering a pressure on a backside surface of a workpiece support, the workpiece support being part of a workpiece carrier to which workpiece is attached. 
   
   
     9. The method of  claim 8  wherein a full face of the conductive surface of the workpiece physically contacts the workpiece surface influencing device during a period of time with the relative motion. 
   
   
     10. The method of  claim 2  wherein a full face of the conductive surface of the workpiece physically contacts the workpiece surface influencing device during a period of time with the relative motion. 
   
   
     11. The method of  claim 2  wherein during the step of electrotreating the displacement varies during the electrotreatment process. 
   
   
     12. The method of  claim 11  wherein during the step of electrotreating the displacement varies in a predetermined manner during the electrotreatment process. 
   
   
     13. The method of  claim 12  wherein the displacement is less at a beginning of the electrotreatment process than at an end of the electro treatment process. 
   
   
     14. The method of  claim 2  wherein the steps of monitoring and using are repeated a plurality of times during the electrotreatment process. 
   
   
     15. The method of  claim 14  wherein the steps of monitoring and using are repeated at periodic intervals during the electrotreatment process. 
   
   
     16. The method of  claim 2  wherein:
 the step of electrotreating uses a spindle motor that rotates the workpiece to establish the relative movement between the workpiece surface influencing device and the conductive surface of the workpiece; and 
 the step of monitoring monitors the signal that corresponds to the torque value of the spindle motor. 
 
   
   
     17. The method of  claim 16  wherein:
 the step of electrotreating further includes using a lateral drive motor to create lateral movement between the conductive surface and the workpiece surface influencing device; 
 wherein the step of monitoring further monitors the signal that also includes a component corresponding to the torque value of the lateral drive motor; and 
 wherein the step of using also uses the monitored signal that includes the component corresponding to the torque value of the lateral drive motor. 
 
   
   
     18. The method of  claim 2  wherein:
 the step of electrotreating includes using a lateral drive motor to create lateral movement between the conductive surface and the workpiece surface influencing device; and 
 wherein the step of monitoring measures the torque value of the lateral drive motor. 
 
   
   
     19. The method of  claim 16  wherein prior to the step of electrotreating there is included the step of moving the workpiece into a zero-touch position relative to the workpiece surface influencing device using a vertical drive motor. 
   
   
     20. The method of  claim 19  wherein at the zero-touch position the spindle motor has a baseline torque value that can be represented as a baseline signal, and wherein during the step of using the monitored signal corresponding to the torque value is compared to the baseline signal to maintain the force between the conductive surface of the workpiece and the workpiece surface influencing device within a predetermined range. 
   
   
     21. The method of  claim 2  wherein the electrotreatment process is an electrochemical mechanical deposition process and the solution is an electrolyte containing a conductor that is deposited onto the conductive surface of the workpiece in the presence of a depositing potential difference. 
   
   
     22. The method of  claim 21  wherein the electrotreatment process further includes an electrochemical mechanical etching process that uses the electrolyte and during which conductive material is removed from the conductive surface of the workpiece in the presence of a removing potential difference that is opposite in polarity from the depositing potential difference. 
   
   
     23. The method of  claim 22  wherein the steps of monitoring and using are repeated during both the electrochemical mechanical deposition process and the electrochemical mechanical etching process. 
   
   
     24. The method of  claim 2  wherein the electrotreatment process is an electrochemical mechanical etching or polishing process and the solution is an etching or polishing solution that is used to remove conductive material from the conductive surface of the workpiece in the presence of a removing potential difference. 
   
   
     25. The method of  claim 1  wherein during the step of electro treating there is included another portion of the electrotreatment process wherein there is not any physical contact between the workpiece surface influencing device and the conductive surface of the workpiece. 
   
   
     26. The method of  claim 1  wherein during the step of electrotreating the force remains within a predetermined range during the electrotreatment process. 
   
   
     27. The method of  claim 1  wherein during the step of electro treating the amount of physical contact varies during the electrotreatment process. 
   
   
     28. The method of  claim 27  wherein during the step of electrotreating the determined amount of physical contact varies in a predetermined manner during the electrotreatment process. 
   
   
     29. The method of  claim 28  wherein the amount of physical contact is less at a beginning of the electrotreatment process than at an end of the electrotreatment process. 
   
   
     30. The method of  claim 1  wherein the step of monitoring is repeated a plurality of times during the electrotreatment process. 
   
   
     31. The method of  claim 24  wherein the step of monitoring is repeated at periodic intervals during the electrotreatment process. 
   
   
     32. The method of  claim 1  wherein:
 the step of electrotreating uses a spindle motor that rotates the workpiece to establish the relative movement between the workpiece surface influencing device and the conductive surface of the workpiece; and 
 the step of monitoring measures the torque value of the spindle motor. 
 
   
   
     33. The method of  claim 32  wherein:
 the step of electro treating further includes using a lateral drive motor to create lateral movement between the conductive surface and the workpiece surface influencing device; and 
 wherein the step of monitoring further measures the torque value of the lateral drive motor. 
 
   
   
     34. The method of  claim 1  wherein the electro treatment process is an electrochemical mechanical deposition process and the solution is an electrolyte containing a conductor that is deposited onto the conductive surface of the workpiece in the presence of a depositing potential difference. 
   
   
     35. The method of  claim 34  wherein the electrotreatment process further includes an electrochemical mechanical etching process that uses the electrolyte and during which conductive material is removed from the conductive surface of the workpiece in the presence of a removing potential difference that is opposite in polarity from the depositing potential difference. 
   
   
     36. The method of  claim 35  wherein the step of monitoring is repeated during both the electrochemical mechanical deposition process and the electrochemical mechanical etching process. 
   
   
     37. The method of  claim 1  wherein the electrotreatment process is an electrochemical mechanical etching process and the solution is an etching solution that is used to remove conductive material from the conductive surface of the workpiece in the presence of a removing potential difference. 
   
   
     38. The method of  claim 1  wherein a full face of the conductive surface of the workpiece physically contacts the workpiece surface influencing device during a period of time with the relative motion. 
   
   
     39. A method of operating upon a plurality of wafers each having a conductive surface using an electrotreatment solution comprising the steps of:
 initializing an electrotreatment process, the step of initializing the electrotreatment process including obtaining a displacement between the conductive surface of each wafer and a workpiece surface influencing device that are in physical contact; 
 performing an electro treatment process on the conductive surface of a first group of the plurality of wafers using a potential difference created between the conductive surface of each wafer and an electrode during at least a portion of the electrotreatment process with the presence of the electrotreatment solution, the electrotreatment process including maintaining relative motion between the workpiece surface influencing device and the conductive surface of the workpiece in the presence of the displacement; 
 reinitializing an electro treatment process, the step of reinitializing the electrotreatment process including obtaining a reinitialized displacement; and 
 performing the electrotreatment process on the conductive surface of a second group of the plurality of wafers using the potential difference created between the conductive surface of each wafer and the electrode during at least a portion of the 
 electrotreatment process with the presence of the electrotreatment solution, the electro treatment process including, maintaining relative motion between the workpiece surface influencing device and the conductive surface of the workpiece in the presence of the reinitialized displacement amount.